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Show 284 MR. A. GARRETT ON THE TERRESTRIAL [Mar. 1, clearly seen where they are encased in the skin. The tips of all the digits are free, including digit in., which has its tip free and projecting beyond the wing-fold. On removing the skin and examining the skeleton, phalanx 1 is distinct, then a rod of cartilage extends to the tip of the projecting fold of skin (a, fig. 4 ). This rod of carti- Fig. 1. Phalanx 1 and the vestigial cartilage of digit in., adult Ostrich. Ph. 1, 1st phalanx; Ph. 2, 2nd phalanx; r, vestigial cartilaginous rod; c, connective tissue. Fig. 2. Pbalanx of digit in. of another adult Ostrich, showing Ph. 2 ankylosed. Fig. 3. Tbe distal part of digit in. in the manus of the embryo (fig. 4). Fig. 4. Ventral view of left manus of embryo, a, free tip of digit in. lage probably represents the remaining phalanges of the digit, which are never definitely differentiated except phalanx 2 : this is ossified in the broader basal third of the rod ; in the embryo, before ossification commences, the basal part is much the broadest. All this points to the conclusion that this cartilaginous rod is a vestigial structure, representing in addition to the second (ossified in the adult), the third probably, and possibly also the fourth, phalanx of digit in. (see figures I and 3). 4. On the Terrestrial Mollusks of the Viti Islands.-Part II.' B y A N D R E W G A R R E T T , of Huahine, Society Islands. (Communicated by Mr. J O H N H. P O N S O N B Y , F.Z.S.) [Eeceived December 8, 1886.] Genus MELAMPUS, Montfort. 1. MELAMPUS LUTEUS, Quoy & Gaimard. Auricula lutea, Quoy & Gaimard, Voy. Astrol. ii. p. 163, pl. 6. figs. 25-27 ; Deshayes, Lam. Hist. viii. p. 388 ; Kiister, Auric. p. 39, pl. 6. figs. 1-3 ; Mousson, Jav. Moll. p. 47, pl. 5. fig. 6. 1 See Part I., siqira, p. 164. |